The present invention relates to techniques for use in interbody spinal procedures and instruments for performing such procedures. More specifically, but not exclusively, the present invention relates to methods and instruments for endoscopic interbody surgical techniques.
Normally intervertebral discs, which are located between endplates of adjacent vertebrae, stabilize the spine and distribute forces between the vertebrae and cushion vertebral bodies. The spinal discs may be displaced or damaged due to trauma, disease or aging. A herniated or ruptured annulus fibrosis may result in nerve damage, pain, numbness, muscle weakness, and even paralysis. Furthermore, as a result of the normal aging processes, discs dehydrate and harden, thereby reducing the disc space height and producing instability of the spine and decreased mobility. Most typically surgical correction of a disc space includes a discectomy (surgical removal of a portion or all of the intervertebral disc material.) The discectomy is often followed by fusion of the adjacent vertebrae to alleviate the pain, abnormal joint mechanics, premature development of arthritis, and nerve damage.
Traditional surgical procedures for correction of disc space pathologies can cause significant trauma to the intervening tissues. These open procedures often require a long incision, extensive muscle stripping, prolonged retraction of tissues, denervation and devascularization of tissue. Most of these surgeries require room time of several hours and several weeks of post-operative recovery time due to the use of general anesthesia and the destruction of tissue during the surgical procedure. In some cases, these invasive procedures lead to permanent scarring and pain that can be more severe than the pain leading to the surgical intervention.
One type of open procedure that attempts to minimize trauma to tissue that occurs with an open procedure uses a transforaminal approach to the disc space. This approach is advantageous in that it allows placement of one or more implants into the disc space with a single incision. However, this approach still suffers from the drawback that the posterior musculature and tissue at the surgical site suffer trauma and damage due to the incision and retraction of tissue at the surgical site.
Minimally invasive surgical techniques are particularly desirable for spinal and neurosurgical applications because of the need for access to locations deep within the body and the danger of damage to vital intervening tissues. The development of percutaneous spinal procedures has yielded a major improvement in reducing recovery time and post-operative pain because they require minimal, if any, muscle dissection and they can be performed under local anesthesia. For example, U.S. Pat. No. 4,545,374 to Jacobson discloses a percutaneous lumbar discectomy using a lateral approach, preferably under fluoroscopic X-ray. This procedure is limited because, among other limitations, it does not provide direct visualization of the discectomy site.
Other procedures have been developed which include arthroscopic visualization of the spine and intervening structure. U.S. Pat. Nos. 4,573,448 and 5,395,317 to Kambin disclose percutaneous decompression of herniated discs with a posterolateral approach. Fragments of the herniated disc are evacuated through a cannula positioning against the annulus. The ""317 Kambin patent discloses a biportal procedure which involves percutaneously placing both a working cannula and a visualization cannula for an endoscope. This procedure allows simultaneous visualization and suction, irrigation and resection in disc procedures. These approaches seek to avoid damage to soft tissue structures and the need for bone removal through a channel. However, these approaches are limited because they do not address, for example, disc space distraction, disc space preparation and implant insertion into the disc space. The approach of the ""317 patent also requires multiple entries into the patient, and the approach of the ""448 patent does not provide for direct visualization of the working space.
Further examples of instruments and methods for performing spinal surgeries using minimally invasive approaches are found in U.S. Pat. Nos. 5,792,044 and 5,902,231 to Foley et al. The present invention is also directed to further improvements and techniques using a minimally invasive approach for performing spinal surgery.
One aspect of the present invention includes inserting one or more interbody fusion devices in a spinal disc space using a minimally invasive, transforaminal approach. Another aspect of the present invention includes inserting performing surgical procedures in a spinal disc space using a minimally invasive, transforaminal approach.
In accordance with another aspect of the invention, a method for performing a surgical procedure in a disc space between adjacent vertebrae is provided. The method includes inserting a cannula to create a working channel through the skin and tissue of a patient using a transforaminal approach to the disc space; inserting a viewing element through the working channel; and preparing the disc space through the working channel for insertion of at least one interbody fusion device. In one form, a facetectomy is performed through the working channel to access the disc space;
In accordance with a further aspect of the invention, a method for inserting at least one interbody fusion device in a disc space between adjacent vertebrae is provided. The method includes creating a working channel to the disc space through the skin and tissue of a patient using a transforaminal approach to the disc space; preparing the disc space through the working channel for bi-lateral placement of the at least one fusion device; and inserting the at least one fusion device into the disc space through the working channel so that the adjacent vertebrae are bi-laterally supported by the at least one interbody fusion device.
In accordance with yet another aspect of the invention, a method of restoring disc height between adjacent vertebrae of a patient is provided. The method includes inserting a cannula through the skin and tissue of the patient to create a working channel to the disc space; distracting the adjacent vertebrae to a disc space height with a distractor extending through the cannula into the disc space; and inserting a shim through the cannula into the disc space adjacent the distractor. The shim has a blade with a height corresponding to the distracted disc space height so that the blade contacts the endplates of the adjacent vertebrae.
In accordance with a further aspect of the invention, a method of preparing a disc space for insertion of an implant between adjacent vertebrae of a patient is provided. The method includes inserting a cannula through the skin and tissue of the patient to create a working channel to the disc space; distracting the disc space to a disc space height by positioning a distractor in the disc space, the distractor being attached to a stem that extends through the working channel, the distractor including a body portion extending between a leading end and a trailing end, the body portion including an upper surface and an opposite lower surface and opposite first and second sidewalls extending between the upper and lower surfaces, the distractor further including a first flange and a second flange each extending proximally from the leading end of the body portion towards the trailing end, the first flange forming a slot with the first sidewall and the second flange forming a slot with the second sidewall; inserting a cutter through the working channel, the cutter having an upper member with an upper cutting edge and a lower member with a lower cutting edge and a pair of opposite sidewalls extending between the upper and lower members; and cutting the adjacent vertebrae by advancing the cutter over the body portion of the distractor such that each sidewall of the cutter is received in a respective one of the slots.
Further objects, features, benefits, aspects and advantages of the present invention shall become apparent from the detailed drawings and descriptions provided herein.